Hardware Timed Over-the-Air Antenna Characterization

ABSTRACT

Antenna characterization systems and methods are described for hardware-timed testing of integrated circuits (IC) with integrated antennas configured for over-the-air transmission and/or reception. An IC to be tested (e.g., the device under test (DUT)) may be mounted to an adjustable positioner in an anechoic chamber. Radio frequency (RF) characteristics (e.g., including transmission characteristics, reception characteristics, and/or beamforming characteristics) of the IC may be tested over-the-air using an array of antennas or probes within the anechoic chamber while continually transitioning the adjustable positioner through a plurality of orientations. Counters and reference trigger intelligence may be employed to correlate measurement results with orientations of the DUT.

FIELD OF THE INVENTION

The present invention relates to the field of semiconductor and/ormobile device testing, and more specifically, to hardware-timedover-the-air antenna characterization.

DESCRIPTION OF THE RELATED ART

Antenna transmission and reception technology is rapidly growing inimportance, e.g., as 5^(th) generation (5G) wireless technology isbecoming more widespread. Current methods for testing integratedcircuits with integrated antennas for transmitting and/or receivingover-the-air signals may be slow and/or expensive, e.g., in part becausethe integrated circuit being tested may need to be positioned accordingto many different orientations and the integrated antennas may need tobe tested according to a plurality of transmit powers and/orfrequencies. Improvements in the field are therefore desired.

SUMMARY OF THE INVENTION

Various embodiments are presented below of antenna characterizationsystems and methods for hardware-timed testing of integrated circuits(IC) with integrated antennas configured for over-the-air transmissionand/or reception. An IC to be tested (e.g., the device under test (DUT))may be mounted to an adjustable positioner in an anechoic chamber. Powerand data connections of the IC may be tested over the fixed conductiveinterface. Radio frequency (RF) characteristics (e.g., includingtransmission characteristics, reception characteristics, beamformingcharacteristics, etc.) of the IC may be tested over-the-air using anarray of antennas or probes within the anechoic chamber whilecontinually transitioning the adjustable positioner through a pluralityof orientations. Counters and reference trigger intelligence may beemployed to correlate measurement results with orientations of the DUT.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredin conjunction with the following drawings, in which:

FIG. 1 illustrates a computer system configured to perform testing of anintegrated circuit, according to some embodiments;

FIG. 2 is an exemplary block diagram of the computer system of FIG. 1,according to some embodiments;

FIG. 3 illustrates multi-antenna beamforming using coarse and fine phaseshifters, according to some embodiments;

FIGS. 4-9 illustrate exemplary integrated circuit devices-under-test(DUTs), according to some embodiments;

FIG. 10 illustrates measurement setup for an entire array test and asingle element test, according to some embodiments;

FIG. 11 is an illustration of a 3D beamforming pattern, according tosome embodiments;

FIG. 12 is a schematic diagram illustrating a typical setup forover-the-air (OTA) antenna testing, according to some embodiments;

FIG. 13 is a detailed illustration of an exemplary adjustablepositioner, according to some embodiments;

FIG. 14 is a schematic diagram illustrating an OTA antenna testing setupusing a combination of a positioning arm and rotary positioner,according to some embodiments;

FIG. 15 is an isometric illustration of an OTA antenna testing setupusing a 3D positioning arm, according to some embodiments;

FIG. 16 is a flowchart diagram illustrating a method for a softwaredriven procedure to characterize over-the-air (OTA) transmissionproperties of an AUT, according to some embodiments;

FIG. 17 illustrates dual channel code tracks of a quadrature encoder,according to some embodiments;

FIG. 18 illustrates how the dual channels of a quadrature encoder leadto incrementing and decrementing a counter value, according to someembodiments;

FIG. 19 is a system diagram illustrating the components and connectionsof a hardware timed over-the-air (OTA) test system, according to someembodiments;

FIG. 20 illustrates a timing diagram of a sequence of signals andcounter transitions in an OTA antenna characterization process;according to some embodiments;

FIG. 21 is a system diagram illustrating the components and connectionsof a hardware timed over-the-air (OTA) test system including a computer,according to some embodiments;

FIG. 22 is a system diagram illustrating the components and connectionsof a hardware timed over-the-air (OTA) test system incorporatingstart/stop triggers, according to some embodiments;

FIG. 23 is a communication flow diagram illustrating a simplified methodfor conducting coordinated OTA antenna measurements, according to someembodiments;

FIG. 24 is a communication flow diagram illustrating a method forconducting coordinated OTA antenna measurements including referencetriggers used by a radio frequency signal analyzer, according to someembodiments;

FIG. 25 is a communication flow diagram illustrating a method forconducting coordinated OTA antenna measurements where some acquisitiontriggers overlap with an ongoing measurement acquisition and do nottrigger a subsequent acquisition, according to some embodiments;

FIG. 26 is a simulated illustration of an antenna transmission powerprofile simulated as a sinc function, according to some embodiments;

FIG. 27 is an illustration of distorted measurement results when theangular velocity is much larger than the inverse of the acquisitiontime, according to some embodiments; and

FIG. 28 is an illustration of high-fidelity measurement results when theangular velocity is comparable to the inverse of the acquisition time,according to some embodiments.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION Terms

The following is a glossary of terms used in the present application:

Memory Medium—Any of various types of non-transitory computer accessiblememory devices or storage devices. The term “memory medium” is intendedto include an installation medium, e.g., a CD-ROM, floppy disks 104, ortape device; a computer system memory or random access memory such asDRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memorysuch as a Flash, magnetic media, e.g., a hard drive, or optical storage;registers, or other similar types of memory elements, etc. The memorymedium may comprise other types of non-transitory memory as well orcombinations thereof. In addition, the memory medium may be located in afirst computer in which the programs are executed, or may be located ina second different computer which connects to the first computer over anetwork, such as the Internet. In the latter instance, the secondcomputer may provide program instructions to the first computer forexecution. The term “memory medium” may include two or more memorymediums which may reside in different locations, e.g., in differentcomputers that are connected over a network.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPGAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic.”

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, such asa user equipment or a cellular network device. Processing elements mayinclude, for example: processors and associated memory, portions orcircuits of individual processor cores, entire processor cores,processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

Software Program—the term “software program” is intended to have thefull breadth of its ordinary meaning, and includes any type of programinstructions, code, script and/or data, or combinations thereof, thatmay be stored in a memory medium and executed by a processor. Exemplarysoftware programs include programs written in text-based programminglanguages, such as C, C++, PASCAL, FORTRAN, COBOL, JAVA, assemblylanguage, etc.; graphical programs (programs written in graphicalprogramming languages); assembly language programs; programs that havebeen compiled to machine language; scripts; and other types ofexecutable software. A software program may comprise two or moresoftware programs that interoperate in some manner. Note that variousembodiments described herein may be implemented by a computer orsoftware program. A software program may be stored as programinstructions on a memory medium.

Hardware Configuration Program—a program, e.g., a netlist or bit file,that can be used to program or configure a programmable hardwareelement.

Program—the term “program” is intended to have the full breadth of itsordinary meaning. The term “program” includes 1) a software programwhich may be stored in a memory and is executable by a processor or 2) ahardware configuration program useable for configuring a programmablehardware element.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

Measurement Device—includes instruments, data acquisition devices, smartsensors, and any of various types of devices that are configured toacquire and/or store data. A measurement device may also optionally befurther configured to analyze or process the acquired or stored data.Examples of a measurement device include an instrument, such as atraditional stand-alone “box” instrument, a computer-based instrument(instrument on a card) or external instrument, a data acquisition card,a device external to a computer that operates similarly to a dataacquisition card, a smart sensor, one or more DAQ or measurement cardsor modules in a chassis, an image acquisition device, such as an imageacquisition (or machine vision) card (also called a video capture board)or smart camera, a motion control device, a robot having machine vision,and other similar types of devices. Exemplary “stand-alone” instrumentsinclude oscilloscopes, multimeters, signal analyzers, arbitrary waveformgenerators, spectroscopes, and similar measurement, test, or automationinstruments.

A measurement device may be further configured to perform controlfunctions, e.g., in response to analysis of the acquired or stored data.For example, the measurement device may send a control signal to anexternal system, such as a motion control system or to a sensor, inresponse to particular data. A measurement device may also be configuredto perform automation functions, i.e., may receive and analyze data, andissue automation control signals in response.

Functional Unit (or Processing Element)—refers to various elements orcombinations of elements. Processing elements include, for example,circuits such as an ASIC (Application Specific Integrated Circuit),portions or circuits of individual processor cores, entire processorcores, individual processors, programmable hardware devices such as afield programmable gate array (FPGA), and/or larger portions of systemsthat include multiple processors, as well as any combinations thereof.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually,” wherein the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Concurrent—refers to parallel execution or performance, where tasks,processes, or programs are performed in an at least partiallyoverlapping manner. For example, concurrency may be implemented using“strong” or strict parallelism, where tasks are performed (at leastpartially) in parallel on respective computational elements, or using“weak parallelism,” where the tasks are performed in an interleavedmanner, e.g., by time multiplexing of execution threads.

Wireless—refers to a communications, monitoring, or control system inwhich electromagnetic or acoustic waves carry a signal through spacerather than along a wire.

Approximately—refers to a value being within some specified tolerance oracceptable margin of error or uncertainty of a target value, where thespecific tolerance or margin is generally dependent on the application.Thus, for example, in various applications or embodiments, the termapproximately may mean: within 0.1% of the target value, within 0.2% ofthe target value, within 0.5% of the target value, within 1%, 2%, 5%, or10% of the target value, and so forth, as required by the particularapplication of the present techniques.

FIG. 1—Computer System

FIG. 1 illustrates a computer system 82 configured to implementembodiments of the techniques disclosed herein. Embodiments of a methodfor (e.g., for production testing of integrated circuits) are describedbelow. Note that various embodiments of the techniques disclosed hereinmay be implemented in a variety of different ways. For example, in someembodiments, some or all of the techniques may be implemented withtextual or graphical programs that may be deployed to, or used toconfigure, any of various hardware devices.

However, while some embodiments are described in terms of one or moreprograms, e.g., graphical programs, executing on a computer, e.g.,computer system 82, these embodiments are exemplary only, and are notintended to limit the techniques to any particular implementation orplatform. Thus, for example, in some embodiments, the techniques may beimplemented on or by a functional unit (also referred to herein as aprocessing element), which may include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors, as well as any combinations thereof.

As shown in FIG. 1, the computer system 82 may include a display deviceconfigured to display a graphical program as the graphical program iscreated and/or executed. The display device may also be configured todisplay a graphical user interface or front panel of the graphicalprogram during execution of the graphical program. The graphical userinterface may comprise any type of graphical user interface, e.g.,depending on the computing platform.

The computer system 82 may include at least one memory medium on whichone or more computer programs or software components according to oneembodiment of the present invention may be stored. For example, thememory medium may store one or more programs, such as graphicalprograms, that are executable to perform the methods described herein.The memory medium may also store operating system software, as well asother software for operation of the computer system. Various embodimentsfurther include receiving or storing instructions and/or dataimplemented in accordance with the foregoing description upon a carriermedium.

Exemplary Systems

Embodiments of the present invention may be involved with performingtest and/or measurement functions; controlling and/or modelinginstrumentation or industrial automation hardware; modeling andsimulation functions, e.g., modeling or simulating a device or productbeing developed or tested, etc. Exemplary test applications includehardware-in-the-loop testing and rapid control prototyping, amongothers.

However, it is noted that embodiments of the present invention can beused for a plethora of applications and is not limited to the aboveapplications. In other words, applications discussed in the presentdescription are exemplary only, and embodiments of the present inventionmay be used in any of various types of systems. Thus, embodiments of thesystem and method of the present invention is configured to be used inany of various types of applications, including the control of othertypes of devices such as multimedia devices, video devices, audiodevices, telephony devices, Internet devices, etc., as well as generalpurpose software applications such as word processing, spreadsheets,network control, network monitoring, financial applications, games, etc.

FIG. 2—Computer System Block Diagram

FIG. 2 is a block diagram 12 representing one embodiment of the computersystem 82 illustrated in FIG. 1. It is noted that any type of computersystem configuration or architecture can be used as desired, and FIG. 2illustrates a representative PC embodiment. It is also noted that thecomputer system may be a general purpose computer system, a computerimplemented on a card installed in a chassis, or other types ofembodiments. Elements of a computer not necessary to understand thepresent description have been omitted for simplicity.

The computer may include at least one central processing unit or CPU(processor) 160 which is coupled to a processor or host bus 162. The CPU160 may be any of various types, including any type of processor (ormultiple processors), as well as other features. A memory medium,typically comprising RAM and referred to as main memory, 166 is coupledto the host bus 162 by means of memory controller 164. The main memory166 may store a program (e.g., a graphical program) configured toimplement embodiments of the present techniques. The main memory mayalso store operating system software, as well as other software foroperation of the computer system.

The host bus 162 may be coupled to an expansion or input/output bus 170by means of a bus controller 168 or bus bridge logic. The expansion bus170 may be the PCI (Peripheral Component Interconnect) expansion bus,although other bus types can be used. The expansion bus 170 includesslots for various devices such as described above. The computer 82further comprises a video display subsystem 180 and hard drive 182coupled to the expansion bus 170. The computer 82 may also comprise aGPIB card 122 coupled to a GPIB bus 112, and/or an MXI device 186coupled to a VXI chassis 116.

As shown, a device 190 may also be connected to the computer. The device190 may include a processor and memory which may execute a real timeoperating system. The device 190 may also or instead comprise aprogrammable hardware element. The computer system may be configured todeploy a program to the device 190 for execution of the program on thedevice 190. The deployed program may take the form of graphical programinstructions or data structures that directly represents the graphicalprogram. Alternatively, the deployed program may take the form of textcode (e.g., C code) generated from the program. As another example, thedeployed program may take the form of compiled code generated fromeither the program or from text code that in turn was generated from theprogram.

FIGS. 3-8—Integrated Circuit (IC) with Antennas

Integrated circuits (IC) with integrated antennas are increasinglycommon. Such ICs are included in many devices and may be configured toperform various functions including wireless communication (e.g.,including transmission and/or reception) and radar. In particular, 5Gwireless communication standards (or other standards) may provide forthe use of millimeter wave (mmW) band wireless signals and beamforming(e.g., directional transmission/reception). It is anticipated thatupcoming cellular communication technologies such as 5G or othertechnologies may use multiple antennas in a coordinated fashion to focusthe transmitted energy toward one spatial point. The pattern formed bythe antenna elements is called a beam and the process of focusing energyis called beamforming. ICs or application specific ICs (ASICs) may be animportant element of many wireless devices configured to communicateusing such standards. For example, an IC with an integrated array ofantennas (e.g., a phased array) may be a common means of including such5G wireless capabilities.

FIG. 3 illustrates an example phase array architecture usable forbeamforming. FIG. 3 illustrates a phase array antenna analog and digitalhybrid architecture, useable to focus the energy of the Tx signal in aspecific spatial location. As illustrated, course phase shifters processa digital signal which is sent through digital-to-analog converters(DACs) and power amplifiers (PAs) before being processed by fine phaseshifters and transmitted by four antennas to form a directional beam.

FIG. 4 illustrates a phased array of antennas which may be incorporatedinto an IC such as a complementary metal-oxide-semiconductor (CMOS)Monolithic Microwave Integrated Circuit (MMIC). The IC may beapproximately 1 cm by 1 cm, among various possibilities.

FIG. 5 illustrates an exemplary IC, including an integrated antennaarray.

FIG. 6 illustrates an exemplary array of 256 antennas on a chip. Itshould be noted that other numbers or configurations of antennas arepossible, as well as other sizes of chips, modules, and/or entire mobiledevices or user equipment devices (UEs).

FIG. 7 illustrates an exemplary IC. As shown, the IC includes multiple(e.g., any desired number) antenna patches mounted to a chip (e.g., aprinted circuit board (PCB), glass wafer, silicon wafer, etc.). Theantenna patches may transmit signals to and from an integrated RF chip(or chips). Note that the RF chip may be included in the chip, but maynot reach the full thickness of the chip. In the illustrated example,the RF chip reaches height h1, which is less than the full height of thechip, h2. The RF chip may be connected to other elements of the IC,e.g., via wired connections.

FIG. 8 illustrates different types of antenna connections of exemplaryICs. In a first configuration, antennas may be embedded in a printedcircuit board (PCB), to which RF chips and a heat sink are mounted. Sucha configuration may be useful for relatively low frequencies, e.g.,approximately 75 GHz, according to some embodiments. In a secondconfiguration, antenna patches may be embedded in package tiles, whichare in turn mounted to RF chips and a (e.g., 2^(nd) level) PCB. The RFchips may be connected (thru the PCB) to a heat sink. Such aconfiguration may be useful for medium frequencies, e.g. 94 GHz, amongvarious possibilities. A third configuration may include antenna patchesembedded in a glass substrate and stacked on RF chips, e.g., above apackage, 2^(nd) level PCB, and heat sink. In a variation, the glasswafer may be mounted on a silicon wafer instead of a package. Suchconfigurations may be useful for higher frequencies, e.g., 110 GHz andabove, among various possibilities.

FIG. 9 illustrates an exemplary mmW IC with an integrated antenna array.As shown, each antenna element (e.g., patch) may have dedicated (e.g.,per element) circuitry. Note that the specific antenna element circuitryshown is exemplary only, and that other antenna element circuitryconfigurations may be used, as desired.

FIG. 10—Testing of mmW IC RF Performance

As demand for ICs with integrated antenna arrays grows, improvements inthe cost of producing and testing such ICs are desired. Testing of mmWICs, e.g., according to conventional techniques, may be challenging forvarious reasons. The radio frequency (RF) performance (e.g., mmWtransmission and reception) of an antenna under test (AUT) or deviceunder test (DUT) may typically be tested over-the-air. Anechoic chambersare commonly used for these tests to avoid interference, e.g., due toreflected signals and multipath effects that can complicate testmeasurements. Beamforming requirements may lead to many antennas on apackage or on a chip and it may be desired to test the beamformingdirectional capabilities of the antenna array/IC. Testing of thebeamforming capabilities may be expensive, time-consuming, and/ordifficult, as measurements may need to be taken from a potentially largenumber of positions, e.g., because the RF performance may varyspatially. In other words, in order to test the spatial RF performance,measurements must be taken in many positions (e.g., in 3 dimensions,e.g., as a function of x, y, and z position). Such detailed spatialtesting may require complex calibration.

FIG. 10 illustrates certain aspects of over-the-air testing of RFperformance, according to some embodiments. An entire array may betested, e.g., using an antenna, e.g., a horn antenna as illustrated orother type of antenna (e.g., patch, dipole, loop, directional array,etc.). In order to test the beamforming capability of the array, theantenna (or antennas) may be positioned at a sufficiently largemeasurement distance that the beam is fully formed. Further,measurements may be taken from a variety of different positions in orderto test the performance of the beam in different directions. An entirearray test may involve relatively high power signals, e.g., +40 dBm, asshown, among various possibilities. Alternatively, single element testsmay be performed. A single element test may require that the hornantenna be far enough away from the antenna element to be tested toavoid RF coupling. This distance may be smaller than the distance forbeam formation, e.g., for an entire array test. A single element testmay not test the beamforming performance of the array. Single elementtests may involve relatively low power signals, e.g., −10 dBm, as shown,among various possibilities.

Because the electromagnetic pattern of a beamforming antenna array ischaracterized over the air (OTA), there are standardized ways to measurethe actual signal strength of antennas in a controlled OTA environment.The antenna under test (AUT) or device under test (DUT) may be placedinside a chamber (possibly an anechoic chamber, to minimize reflectionsand interference from outside sources, though other types of chambersmay be used, as desired). A signal may be transmitted by the antenna andone or more receive antennas (also located inside the chamber) maycapture the received power. The AUT may then be moved across adiscretized spatial profile. As these points are measured, a 3D patternis created, as illustrated in FIG. 11. According to various embodiments,the measurement method may vary in the type of chamber used, thegeometry and sequence of the measurement grid (e.g., equal angles,spiraling down a sphere, single cross plane points, etc.), and thecalibration method used for the measurement process.

Additionally, while some embodiments describe a DUT or AUT thattransmits a beamforming signal that is measured by one or more receiverswithin the chamber, an inverse setup is also possible where over-the-air(OTA) reception properties of the DUT are tested and/or characterized.For example, one or more transmitters may be positioned within thechamber, and the DUT may receive transmissions of the one or moretransmitters, wherein reception characteristics of the DUT receiver maybe characterized from a plurality of directions. As may be appreciatedby one of skill in the art, methods and systems described herein may beadapted to embodiments where properties of one or more OTA receivers ofthe DUT are characterized. Accordingly, descriptive instances of an AUTand one or more receive antennas of the anechoic chamber may berespectively replaced with a receiver of a DUT and one or more transmitantennas of the anechoic chamber, according to some embodiments.

FIG. 12—Anechoic Chamber Antenna Measurement Setup

FIG. 12 is a schematic diagram illustrating a typical setup for OTAantenna testing, according to some embodiments. As illustrated, theadjustable positioner 3002 may rotate along two orthogonal axes (or onlyone axis, in some embodiments) to capture the output pattern of the AUT2608 according to a plurality of spatial orientations. Dampeners 2602 ofthe anechoic chamber may prevent reflections and interference of theoutput pattern, and the receive antenna 2604 may measure the output ofthe AUT. In previous implementations, the movement may be controlled viatest sequencing software that ensures that the turntable is in the rightangle, after which the RF measurement may take a power measurement. Amore detailed illustration of an exemplary adjustable positioner 3002 isshown in FIG. 13, where the arrows indicate the two orthogonal axes ofrotation of the positioner. As may be appreciated by those of skill inthe art, any of a variety of types of adjustable positioners may be usedto hold and orient the AUT or DUT according to a plurality oforientations, and the examples illustrated for the adjustable positionerin FIGS. 12 and 13 are exemplary only, and are not intended to limit thescope of the disclosure.

FIG. 14 in an isometric illustration of an OTA testing setup wherein anadjustable positioning arm is combined with DUT rotation. For example,each of the reception antenna(s) and the DUT may be separately rotatableto a plurality of orientations.

In other embodiments, as illustrated in FIG. 15, a mmW array of antennasmay be tested using a 3-D positioning arm, wherein the AUT is stationarybut the receive antenna(s) rotate through a sequence of positions. FIG.15 is a schematic illustration of an anechoic chamber configured with a3-D positioning arm. Such 3-D positioning arm may operate in an anechoicchamber, e.g., sized for 18-87 GHz frequencies, among variouspossibilities. The 3-D positioning arm may perform spiral scanning,e.g., to take measurements at any number of locations, e.g., using ahorn antenna. As illustrated in FIG. 15, the AUT may be mounted in thechamber, and may be configured to transmit a signal in a beamformingpattern (e.g., in a tested beam form). The 3-D positioning arm may movea horn antenna in various positions in the chamber for measurements.

A low reflection antenna (e.g., a small radar cross section) may be usedfor testing, e.g., in order to minimize effects on the fields. Themeasurements may be taken in the near field (e.g., in the Fresnel zoneof the near field). Tests may be performed to measure magnitude andphase of the signal/field at any number of locations. The far fieldpattern may be computed based on the near field measurements. Theconversion of near-field to far-field may be accomplished using anyappropriate calculation approach. Such calculations may be relativelystraight forward if the antenna pattern/configuration is known, or morecomplex for an arbitrary pattern. Plots of the far field pattern may begenerated. Such a 3-D positioning system may be useful for design andcharacterization tests, however the equipment may be relativelyexpensive and the tests may be time consuming. First, the testingprocess itself may take significant time, e.g., because of the need tomove the 3-D positioning arm through a large number of positions to testeach DUT. Second, the anechoic chamber may need to be large enough toallow for measurements to be taken in enough positions (e.g., in 3-Dspace) to compute the far field pattern. In some embodiments, theanechoic chamber may be large enough so that measurements may be takenin the radiating far field. In some embodiments, a compact antenna testrange (CATR) may employ a reflector to reduce the far field distance,enabling far field measurements within a smaller anechoic chamber.

FIG. 16—Legacy Method for Software-driven AUT Characterization

FIG. 16 is a flowchart diagram illustrating a legacy method for asoftware driven procedure to characterize over-the-air (OTA)transmission properties of an AUT. As illustrated, a positioningmechanism is rotated according to a precalculated angle in the sphere(typically controlled via ethernet), after which the RF characteristicsare measured (typically power, error vector magnitude (EVM), or adjacentchannel power (ACP), among other possibilities). The process may repeatuntil all predetermined angles are reached and measured. The loopprocess may have other sweep items like “input RF power” or “frequency”,and these items may further increase the duration of the process. AUTcharacterization often performs measurements of total radiated power.Performing a total radiated power measurement typically involvesphysically rotating the AUT to a large number of orientations, as theaccuracy of this measurement increases with the number of sample pointstaken around the sphere.

These legacy procedures are typically non-deterministic and executedthrough software-timed procedures. In addition, the methods rely onstart/stop motion in order to allow sufficient settling and pause timeat a given position for the measurement system to perform an acquisitionwith sufficient time accuracy. These methods are very slow, andcharacterization test times are critical for designers. The softwareinteraction is a large component of the latency, and embodiment hereinimprove on these legacy methods by implementing a hardware-timed closedloop system. The total test time for legacy software-timed method may beestimated as:

T _(TOTAL)=Σ_(i=0) ^(M)(t _(positioner(i)) +t _(RF(i)))

Where t_(positioner) is the individual time to translate to and settleat each measurement position and t_(RF) is the time to compute and fetcha single RF measurement. In some embodiments described hereint_(positioner) may be reduced, thereby reducing the latency of themeasurement acquisition process, by continually transitioning the DUTthrough a plurality of orientations without halting the motion of theDUT between orientations. For example, a continuous transition processmay remove the settle time of the DUT.

Additionally, in a software-timed measurement acquisition method,significant latency may be introduced through t_(RF) due to softwareinterrupts, operating system latency, computational latency, and otherfactors. Embodiments herein describe systems and methods for performinghardware-timed OTA antenna characterization, where direct hardwaresignaling between structural elements of the antenna characterizationsystem may automatically trigger method steps of the measurementacquisition process without introducing software or processing latency.For example, hardware-triggered digital feedback from the adjustablepositioner may be used to keep track of the correlation between theorientation of the DUT and the corresponding measurement acquisitions,without pausing the acquisition process with intermittent softwaredirectives. Accordingly, the time and computational resources used forthe measurement acquisition process may be dramatically reduced.

Encoding Orientation of the Adjustable Positioner

A variety of encoding schemes may be used to track the orientation ofthe adjustable positioner. A quadrature encoder is a common type ofincremental encoder that uses two output channels (A and B) to senseposition. Using two code tracks with sectors positioned 90 degrees outof phase, the two output channels of the quadrature encoder indicateboth position and direction of rotation. As illustrated in FIG. 17, if Aleads B, for example, the disk is rotating in a clockwise direction. IfB leads A, then the disk is rotating in a counter-clockwise direction.By monitoring both the number of pulses and the relative phase ofsignals A and B, both the position and direction of rotation may betracked.

In some embodiments, a quadrature encoder may also include a thirdoutput channel, called a zero or index or reference signal, whichsupplies a single pulse per revolution. This single pulse may be usedfor precise determination of a reference position.

In some embodiments, the positioner may be configured to export digitallines whose length are proportional to the speed of the positioner tosignal when and how fast the positioner is moving.

Hardware Timed OTA Antenna Characterization

According to exemplary embodiments, the OTA antenna characterizationprocess may be sped up substantially with a hardware-timed measurementsystem that incorporates a deterministic closed control loop between themeasurement system and the motion of the AUT. Most rotation mechanisms(e.g., the adjustable positioner) use servo motors or some sort ofencoders to determine the exact position. These devices may use positiontracking as a way to determine their location in the circle of motion.These signals are commonly internal to the rotation mechanism.Embodiments described herein redesign a rotation mechanism to export theencoder signals to be used in synchronization of the OTA antennacharacterization process.

The rotation mechanism of the adjustable positioner may consist of twodegrees of freedom (e.g., to orthogonal axes of rotation), where eachdegree of freedom has a feedback mechanism. Alternatively, the rotationmechanism may only utilize a single axis of rotation. As illustrated inFIG. 18, a quadrature encoder that provides digital signals may be usedby a digital counter to keep track of the position (count) of themotors. As illustrated, the counter value may be incremented at thebeginning of each pulse on Channel A when Channel A is leading Channel Bby 90 degrees. Conversely, when Channel B is leading Channel A, thecounter value may be decremented at the end of each Channel A pulse(e.g., because the rotation mechanism is moving in the oppositedirection when Channel B leads Channel A).

The counter value may keep track of the angular position of the rotationmechanism at all times. In some embodiments, these changes of count maybe consolidated to create a single signal that is called the “mastertrigger”. It may be achieved by programming the counters to output adigital signal every time the count changes. Alternatively, a digitaledge detection circuitry may be used, which are used in manycommercially available data acquisition cards. The “master trigger” maybe further divided in frequency simply to have a way to reduce thenumber of triggers that the RF subsystem gets. In other words, afrequency divisor may be employed within the counter apparatus such thatonly every N^(th) trigger leads to an acquisition measurement.

FIG. 19—Connection diagram of Semiconductor Test System

FIG. 19 is a system diagram illustrating the components and connectionsof a semiconductor test system, alternatively referred to as an antennacharacterization system (ACS), according to exemplary embodiments. Asillustrated, the radio frequency (RF) measurement system, comprising anRF signal analyzer coupled to reference triggers in and out, may becoupled through an ethernet (ENET) connection to the motor controldevice that controls the motion of the motors of the adjustablepositioner. The motor control device may comprise a motion controlprocessor that is configure to direct motion of the adjustablepositioner. For example, the motor control device may be a NationalInstruments IC-3120 device, or another type of motor control device,according to various embodiments. As illustrated, the motor control maycommunicate with two motor drives through an ethernet for controlautomation technology (ECAT) connection to direct the motion of themotor drives. The two motor drives may be configured to rotate theadjustable positioner according to two orthogonal axes of rotation, asillustrated by the two circular arrows on the adjustable positioner3002. Each of the motor drives may be in turn coupled to the counterapparatus, each through two encoder channels A and A′. As described ingreater detail above in reference to the quadrature encoder scheme, thetwo signaling channels between the motor drives of the adjustablepositioner and the counter apparatus may enable a determination of thedirection of motion of the adjustable positioner.

The counter apparatus may contain two separate counters (e.g.,corresponding to the two axes of rotation of the adjustable positioner),and may additionally contain one or more edge detection apparatuses todetect the edge of a modification instance of one or the other of thecounters. As described in greater detail below, the edge detectionapparatus may transmit a master trigger to one or more frequencydivisors, to potentially lead to a measurement acquisition. Thefrequency divisor may be configured to only allow every N^(th) mastertrigger to lead to a measurement acquisition. For example, the frequencydivisor may keep a running tally of received master triggers, and maytransmit every N^(th) master trigger to the RF measurement system totrigger the RF signal analyzer to perform a measurement acquisition.

As illustrated, the RF signal analyzer may employ a dual “triggerreference in” and “trigger reference out” system to ensure that samplesare not taken from positions where there is no acquisition. For example,when the counter apparatus sends an acquisition trigger to the “triggerreference in” (TRI) port of the RF signal analyzer, the TRI may forwardthe acquisition trigger to the trigger reference out (TRO) only when theRF signal analyzer initiates a measurement acquisition of the DUT, andmay transmit a reference trigger out back to the counter apparatus, toinform the counter apparatus that a measurement acquisition has beeninitiated. On the other hand, if the RF signal analyzer has notcompleted a previously initiated measurement acquisition when the TROforwards the acquisition trigger to the RF signal analyzer (e.g., if theRF is still conducting an ongoing, previously initiated measurementacquisition when the acquisition trigger is received), the TRO mayrefrain from forwarding the reference trigger out to the counterapparatus. In this case, a measurement was not initiated during thecurrent value of the counter (or counters), and the counter apparatusmay likewise not forward the current value of the counter (or counters)to the computer for correlation with measurement results, avoidingerrors in the correlation calculation.

FIG. 20 illustrates a timing diagram of a sequence of signaling andcounter modifications in an exemplary acquisition process. Asillustrated, a first motor (e.g., a motor directing motion of theadjustable positioner about a first axis of rotation) transmits periodicsignals through two channels, A₁ and A₁′. The signals are transmitted toa first counter of the counter apparatus (“Counter1”), which incrementsthe counter at the front edge of each instance of a signal from motor1's encoder A₁ channel. Note that the counter is incremented in thiscase because the encoder A₁ channel leads the encoder A₁′ channel by 90degrees. Conversely, if the encoder A₁′ channel led the encoder A₁channel by 90 degrees, the counter would be decremented at the back edgeof each signal from the encoder A₁ channel.

Similarly, motor 2 (directing rotation of the adjustable positioneraround a second axis, orthogonal axis of rotation) transmits signalsthrough two channels, A₂ and A₂′, to the second counter of the counterapparatus, which likewise modifies the second counter according to theleading edge of the channel A₂ signals. As used herein, the term“channel” may refer to either of the multiple quadrature encoderchannels corresponding to a particular motor, or respective channels ofthe two motors. According to exemplary embodiments, there may be fourchannels used for transmitting signals by the adjustable positioner: A¹,A₁′, A₂, and A₂′. More generally, any number of motors with respectivechannels, and any number of channels per each motor may be used, asdesired. Each of the counter outputs their respective first and secondcounters which are combined to a master trigger. In FIG. 20, thefrequency divisor is a trivial N=1 frequency divisor, such that everyinput master trigger leads to the output of an acquisition trigger.Alternatively, if an N=2 frequency divisor was employed (not illustratedin FIG. 20), only every other signal in the master trigger would lead tothe output of an acquisition trigger.

FIG. 20 additionally illustrates the duration of a sequence ofmeasurement acquisitions. Additionally, it is illustrated how when anacquisition trigger is sent to the RF signal analyzer while a previousmeasurement acquisition is still ongoing (e.g., the second acquisitiontrigger is sent while the p1 acquisition is still ongoing), a referencetrigger out is not sent to the counter apparatus. In this manner, therecorded counts 1 and 2 will each correspond to a unique measurementacquisition, and counts 1 and 2 will not be recorded when a measurementacquisition does not take place. In post processing, a computer may thencorrelate the result of each measurement acquisition with a recordedcount of each of counters 1 and 2, to determine the position of theadjustable positioner corresponding to each measurement result. In otherwords, for each RF measurement acquisition, corresponding measurementsmay be computed (described as p_(i) in FIG. 20), the counter values maybe stored at the same time, and a table may be populated. Table 1,below, illustrates an example.

TABLE 1 Example Results of OTA Antenna Characterization AzimuthElevation Counts/ Azimuth Elevation RF Count Count Degree Angle AnglePower 1 0 10 0.1 0 p1 2 1 10 0.2 0.1 p2 3 1 10 0.3 0.1 p3 4 1 10 0.4 0.1p4 5 2 10 0.5 0.2 p5 6 2 10 0.6 0.2 p6 23 5 10 2.3 0.5 p7 34 5 10 3.40.5 p8 45 15 10 4.5 1.5 p9 56 15 10 5.6 1.5 p10 67 20 10 6.7 2 p11 78 2410 7.8 2.4 p12 89 28 10 8.9 2.8 p13 100 32 10 10 3.2 p14 111 36 10 11.13.6 p15 122 40 10 12.2 4 p16 133 44 10 13.3 4.4 p17 144 48 10 14.4 4.8p18 155 52 10 15.5 5.2 p19 166 56 10 16.6 5.6 p20 177 60 10 17.7 6 p21188 64 10 18.8 6.4 p22 199 68 10 19.9 6.8 p23 210 72 10 21 7.2 p24 22176 10 22.1 7.6 p25 232 80 10 23.2 8 p26 243 84 10 24.3 8.4 p27 254 88 1025.4 8.8 p28 265 92 10 26.5 9.2 p29

In some embodiments, a translation from counter values to [Azimuth,Elevation] pair may be computed. This may be dependent on the mechanicaldesign of the positioner and the feedback mechanism.

Advantageously, embodiments described herein avoid utilizing softwareinteractions to perform the sequence of orientations of the AUT and theassociated measurement acquisitions. An important distinction ofembodiments described herein is that the feedback mechanism (counters)are being sampled at the time of the RF measurement, which may achievebetter accuracy than other types of synchronization.

An additional improvement of embodiments described in regard to thespeed of the AUT characterization process is that adjustable positionermay transition between a plurality of orientations of the AUTcontinuously (i.e., without halting the motion between orientations). Insoftware triggered implementations, the error between the hardware andthe software triggering is typically too large to enable repeatableresult with a continuous, non-halting motion of the adjustablepositioner. Because the system is connected on hardware, latency anderror are sufficiently low such to allow repeatable results withouthalting the motion of the positioner during the AUT characterizationprocess.

FIG. 21 is a similar system diagram to FIG. 19, where the instrumentcontrolling computer is included. In particular, FIG. 21 illustrateshow, in some embodiments, a computer may be used to direct themeasurement acquisition process described in FIG. 19. Additionally, FIG.21 illustrates a motion detection apparatus which may receive signalsfrom motors 1 and 2 as well as from the counter apparatus to determine(e.g., by the motion detection logic) when to transmit a master trigger(i.e., an acquisition trigger) to the RF measurement system. In someembodiments, the performing of the measurement acquisition process maybe controlled by a programmable hardware element of the computer. Inother words, in some embodiments, at least some of the methods disclosedherein may be implemented and/or controlled in programmable hardware,such as a field programmable gate array (FPGA). Other configurations ofthe system diagram are also possible. For example, one or more of thecounter apparatus, the motor control, the motion detection apparatus,and the RF signal analyzer/RF measurement system may be included assoftware within the computer, or they may be separate hardware elements(e.g., such as PXI cards in a modular chassis, for example). In general,the structural elements of an RF measurement system, a counterapparatus, and motor control may take a broad variety of forms in eithersoftware or hardware. The terms “RF measurement system”, “counterapparatus”, “motor control”, and “motion detection apparatus” areintended to be functional descriptors of the role played by therespective entities in the measurement acquisition process, and are notintended to limit their implementation in various embodiments to aspecific type of hardware or software.

FIG. 22 is a system diagram similar to FIG. 21 that additionallyillustrates a capability of the system to sequentially start and stopthe motion of the adjustable positioner during the measurementacquisition process, according to some embodiments. In some embodiments,the duration of each measurement acquisition may be long enough suchthat it may be desirable for the adjustable positioner to temporarilyhalt the motion of the DUT while each measurement is being acquired, andtransition to a subsequent orientation after completion of themeasurement acquisition. Alternatively, or additionally, it may bedesirable to perform a plurality of measurements at each orientation ofthe DUT (e.g., it may be desirable to measure transmission properties ofthe DUT at a plurality of transmission power levels, or at a pluralityof different frequencies, for each orientation, among otherpossibilities), and it may be desirable for the adjustable positioner toremain at a particular orientation until the plurality of measurementacquisitions are complete.

As illustrated in FIG. 22, the counter apparatus may transmit a digitalstop trigger to the motion control processor concurrently with everytransmission of an acquisition trigger to the RF measurement system, sothat the motion control processor halts the motion of the adjustablepositioner at the initiation of each measurement acquisition. in someembodiments, the counter apparatus may wait a predetermined period oftime after transmitting the digital stop trigger for the adjustablepositioner to settle into a stable position before transmitting theacquisition trigger to the RF measurement system. Alternatively, thecounter apparatus may transmit the digital stop trigger to the motioncontrol processor upon reception of a reference trigger out signal fromthe RF measurement system, so that the counter apparatus will onlyinstruct the motion control processor to halt the motion of theadjustable positioner when an acquisition trigger has actually led to ameasurement acquisition by the RF measurement system.

As further illustrated in FIG. 22, the RF measurement system maytransmit a digital start trigger to the motion control processor toresume motion when the RF measurement system has ended (i.e., completed)its measurement acquisition. In response the motion control processormay direct the adjustable positioner to transition to a subsequentorientation in the sequence. Advantageously, the implementation ofstart/stop triggers may improve flexibility regarding the number andduration of measurements acquired on a single position. Additionally,utilization of hardware-timed signaling between the structural elementsof the measurement acquisition system may reduce latency that wouldotherwise be introduced through software interaction.

FIGS. 23-25—Communication Flow Diagrams for Measurement Acquisition

FIG. 23 is a communication flow diagram illustrating a simplified methodfor conducting coordinated OTA antenna measurements, according to someembodiments. As illustrated, a computer may configure and arm a radiofrequency (RF) signal analyzer for an upcoming measurement acquisitionprocess of a device-under-test (DUT) or an antenna-under-test (AUT). TheRF signal analyzer may configure its measurement acquisition andtriggering mechanisms, and wait for a “Ref Trig In” to conduct ameasurement acquisition. The RF signal analyzer may inform the computerwhen it is ready and configured. The computer may also arm the counterapparatus, which may be initialized and may inform the computer after ithas been initialized. The computer may also configure the motion controlapparatus with a position sweep protocol. and the motion controlapparatus may inform the computer when it and the adjustable positionerare ready to start a position sweep. For example, the computer mayinform the motion control apparatus of a starting position for one ormore angles of the adjustable positioner, as well as a sequence ofmotion sweeps of the one or more motors through a sequence of differentorientations of the DUT.

The computer may then initialize the position sweep, and the motioncontrol apparatus may direct the adjustable positioner to beginorienting the DUT through a plurality of different orientations. Theadjustable positioner may continually transition between orientations,without halting the motion of the positioner between orientations. Inresponse to the adjustable positioner reaching each of the pluralityorientations, signals through one or more channels may be automaticallysent from the adjustable positioner to the counter apparatus. Thecounter apparatus may use these signals to modify one or more counterscorresponding to one or more respective axes of rotation of theadjustable positioner. For example, the counter apparatus may incrementor decrement its one or more counters based on the signals received(e.g., according to the quadrature encoding scheme described above). Thecounter apparatus may transmit the modified counter to the computer,which may read the counter value and translate the value into an angleand orientation of the adjustable positioner. The counter apparatus mayemploy an edge detector, to detect either the front or back edge of acounter (e.g., depending on whether the counter is incremented ordecremented), to determine the precise instant when the counter wasmodified.

In response to an edge detection, the counter apparatus may transmit anacquisition trigger to the RF signal analyzer, which may cause the RFsignal analyzer to perform a measurement acquisition of the DUT (denotedas “RF signal acquisition” in FIG. 23). The RF signal analyzer maytransmit the result of the measurement acquisition to the computer,which may read the result and correlate the result with the receivedcounter value to determine the orientation of the adjustable positionerat the time of the measurement. After a sequence of many such correlatedmeasurement acquisitions, the computer may populate a table ofmeasurement results and their associated DUT orientations, and may storethe table in memory.

FIG. 24 is a communication flow diagram illustrating a method forconducting coordinated OTA antenna measurements including referencetriggers used by a radio frequency signal analyzer, according to someembodiments. FIG. 24 is similar to FIG. 23, but FIG. 24 explicitlydescribes the role played by the frequency divisor of the counterapparatus and the reference triggers in and out of the RF signalanalyzer. As illustrated, the frequency divisor filters out every N^(th)acquisition trigger received from the counter apparatus (every 4^(th)acquisition trigger in the illustrated example of FIG. 24, though othervalues of N are also possible). As illustrated, every 4^(th) acquisitiontrigger is forwarded to the reference trigger in (“Ref Trig In”) port ofthe RF signal analyzer. The Ref Trig In forwards the acquisition triggerto the Ref Trig Out port, which in turn triggers a measurementacquisition. Importantly, if a measurement acquisition is initiated, theRef Trig Out also forwards a trigger back to the counter apparatus,which instructs the counter apparatus to transmit the current value ofthe counter to the computer for correlation with the measurement result.In this manner, a counter value is transmitted to the computer forcorrelation with a measurement result only when a measurementacquisition has been initiated.

FIG. 25 is a communication flow diagram illustrating a method forconducting coordinated OTA antenna measurements where some acquisitiontriggers overlap with an ongoing measurement acquisition and do nottrigger a subsequent acquisition, according to some embodiments. FIG. 25is similar to FIGS. 23 and 24, but FIG. 25 illustrates explicitly howthe method may be utilized to accommodate two counters corresponding totwo different axes of rotation of the adjustable positioner.Additionally, FIG. 25 illustrates how the described methods mayaccommodate a circumstance where an acquisition trigger is received byRF signal analyzer before a previously initiated and ongoing measurementacquisition is completed.

As illustrated, FIG. 25 shows that counter 1 and counter 2(corresponding respectively to two different axes of rotation of theadjustable positioner) may separately be incremented at two different(and potentially non-commensurate) rates. As illustrated, a modificationto either counter 1 or counter 2 may lead the edge detector to transmitan acquisition trigger to the frequency divisor, and the frequencydivisor may forward every N^(th) acquisition trigger received to the RefTrig In of the RF signal analyzer to perform a measurement acquisition.In the illustrated example of FIG. 25, the first such acquisitiontrigger received by Ref Trig Out leads to a measurement acquisition, theresult of which is transmitted to the computer, and additionallyinstructs the counter apparatus to transmit the current value of counter1 and counter 2 to the computer for correlation with the respectivemeasurement result.

The second acquisition trigger that is transmitted to Ref Trig In,however, is received by Ref Trig Out before the first RF signalacquisition is completed (i.e., it is received during a previouslyinitiated and ongoing RF measurement acquisition). Accordingly, Ref TrigOut does not initiate a subsequent measurement acquisition, and thecounter apparatus is not instructed to transmit the current values ofcounter 1 and counter 2 to the computer for correlation with measurementresults. In this manner, even though the sequence of acquisition triggertransmissions by the counter apparatus to the RF signal analyzer may beaperiodic (e.g., because the rate of transmissions depends on theconvolution of two different and potentially non-commensurate periods.Namely, the two periods of counter modification of counters 1 and 2),each set of counter values received by the computer will be correlatedto a single corresponding measurement result.

The following numbered paragraphs describe additional embodiments of theinvention.

In some embodiments, a semiconductor test system (STS), comprises ananechoic chamber, a counter apparatus, a radio frequency (RF) signalanalyzer coupled to one or more receive antennas and the counterapparatus, an adjustable positioner coupled to the counter apparatus,and a computer comprising a processor and coupled to each of theadjustable positioner, the counter apparatus, and the RF signalanalyzer. The one or more receive antennas may be positioned inside theanechoic chamber, and the RF signal analyzer may be configured toacquire RF measurements made by the one or more receive antennas oftransmissions of an antenna under test (AUT) or a device-under-test(DUT). The computer may initialize a measurement process on the DUT orAUT according to the following sequence of steps.

In some embodiments, an apparatus configured for inclusion within acomputer, wherein the computer is comprised within a semiconductor testsystem (STS), comprises a memory and a processing element incommunication with the memory. The memory may store program instructionsthat are executable by the processing element to cause the computer andthe STS to initialize a measurement process on the DUT or AUT accordingto the following sequence of steps.

The STS may initialize a measurement process on the AUT by causing theadjustable positioner to continually transition the AUT inside theanechoic chamber through a plurality of orientations without halting themotion of the adjustable positioner between orientations. Saidcontinually transitioning the AUT through the plurality of orientationsmay be performed at a speed such that the time between successive signaltransmissions through each of the one or more channels is greater thanan acquisition time of each of the RF measurements.

The adjustable positioner may be configured to automatically transmit asignal through one or more channels to the counter apparatus in responseto the adjustable positioner positioning the AUT according to each ofthe plurality of orientations. The adjustable positioner may provide thesignals to the counter apparatus via direct hardware signaling. In otherwords, the adjustable positioner may communicate the signals directly tothe counter apparatus, without introducing software latency. Rather, thesignals may be communicated directly through a wired or wirelessconnection, and the signals may automatically cause the counterapparatus to perform the following steps.

The one or more channels may comprise a first channel and a secondchannel of a quadrature encoder scheme, wherein said modifying the firstcounter comprises incrementing or decrementing the first counter, andwherein a relative phase between respective signals of the first channeland the second channel determines whether the counter apparatusincrements or decrements the first counter.

For embodiments, where modifying the first counter comprisesincrementing or decrementing the first counter, the counter apparatusmay comprise an edge detector configured to detect the front edge intime of an incremented first counter and the back edge in time of adecremented first counter. In these embodiments, said transmitting themodified first counter to the computer and said transmitting the firstacquisition trigger to the RF signal analyzer may be performed by theedge detector in response to detecting the front edge of the incrementedfirst counter or the back edge of the decremented first counter.

In response to receiving the signals from the adjustable positionerthrough the one or more channels, the counter apparatus may beconfigured to modify a first counter, transmit the modified firstcounter to the computer, and transmit a first acquisition trigger to theRF signal analyzer, wherein said modifying the first counter,transmitting the modified first counter, and transmitting the firstacquisition trigger occur a plurality of times at different respectiveorientations of the AUT. Similar to the connection between theadjustable positioner and the counter apparatus, the counter apparatusmay the first acquisition triggers to the RF signal analyzer throughdirect hardware signaling, such that only a very small (e.g.,microseconds or smaller) amount of latency is introduced incommunicating the acquisition trigger to the RF signal analyzer.

In some embodiments, in response to receiving the signals from theadjustable positioner, the counter apparatus may modify a secondcounter, transmit the modified second counter to the computer, transmita second acquisition trigger to the RF signal analyzer. Said modifyingthe second counter, transmitting the modified second counter, andtransmitting the second acquisition trigger may occur a plurality oftimes at different respective orientations of the AUT. The secondcounter may be associated with a different axis of rotation of theadjustable positioner than the first counter.

The counter apparatus may comprise a frequency divisor, and saidtransmitting the modified first counter to the computer and saidtransmitting the first acquisition trigger to the RF signal analyzer maybe performed by the frequency divisor for every N^(th) modified firstcounter and every N^(th) first acquisition trigger, where N is apositive integer.

In some embodiments transmitting the modified first and second countersto the computer and said transmitting the first and second acquisitiontriggers to the RF signal analyzer is performed by the frequency divisorfor every N^(th) modified first or second counter and every N^(th) firstor second acquisition trigger, where N is a positive integer. In otherwords, the frequency divisor may count reception of both first andsecond acquisition triggers, and may transmit every N^(th) acquisitiontrigger, regardless of whether the N^(th) acquisition trigger is a firstor second acquisition trigger.

The RF signal analyzer may be configured to acquire an RF measurement oftransmissions of the AUT and relay the result of the RF measurement tothe computer in response to receiving each of the plurality of firstacquisition triggers.

In some embodiments, said acquiring an RF measurement by the RF signalanalyzer is not initiated when one of the plurality of first acquisitiontriggers is received during a previously initiated and ongoing RFmeasurement acquisition. In these embodiments, the RF signal analyzermay be further configured to transmit a reference trigger to the counterapparatus in response to initiating each RF measurement acquisition, andsaid transmitting the modified first counter to the computer by thecounter apparatus may be performed further in response to the counterapparatus receiving the reference trigger from the RF signal analyzer.In these embodiments, the RF signal analyzer may refrain fromtransmitting the reference trigger to the counter apparatus whenreception of a respective first acquisition triggers does not result ininitiation of acquisition of the RF measurement (i.e., when anacquisition trigger is received by the RF signal analyzer before aprevious ongoing acquisition is complete).

The computer may be further configured to correlate the modified firstcounters received from the counter apparatus with the results of the RFmeasurements to determine an orientation of the plurality oforientations of the AUT corresponding to each of the results of the RFmeasurements, and output a correlated list of results of the RFmeasurements and their respective orientations of the AUT. The list ofresults may be stored in a memory.

Accuracy of RF Measurements

Accuracy of the recorded positions of the adjustable positioner may beadversely affected by several factors. Depending on the encodersresolution and the N-decimation factor, the exact angle might not fallin an exact point. This may cause some small correlation issues with theother (second) rotation mechanism as the data comparison may have asmall angle deviation error. Additionally, there may be a delay betweenthe count number and the RF acquisition. However, even if this is asignificant error, it is fixed and may be corrected during calibrationof the delays of the system.

In some embodiments, the largest error may be the RF acquisitionduration compared to the angular velocity of the adjustable positioner.Consider a perfect simulation of the power of an antenna simulated as asinc function, as illustrated in FIG. 26. The relative magnitudes of theangular velocity and the inverse of the acquisition time may affect themeasurement of the power. If angular velocity ω_(r) is much greater thanthe inverse of the acquisition time, the ideal power profile shown inFIG. 26 may be distorted, as shown in FIG. 27. FIG. 27 illustrateddistorted measurement results when the angular velocity is 50× largerthan the inverse of the acquisition time.

Simulation results show that when the angular velocity is close to theinverse of the RF acquisition time, then the results are wellcorrelated, as illustrated in FIG. 28. The mean squared error for FIG.28 is less than 5e-6.

Power is a common measurement in OTA antenna characterization. Power maytypically be computed for a mmWave measurement with about 100 μs of rawdata. This means that the angular velocity may be as high asapproximately 10,000 degrees per second without introducing significantdistortion. In turn, this means that a very detailed grid of 1296 points(half sphere every 5 degrees on azimuth and elevation), may be computedin about 1.3 seconds using an appropriate trajectory. The number ofcollected points may be many more but to manage the data better it istypically sufficient to keep results for every 5 degrees and drop allother results.

Some advantages of embodiments described herein may be summarized asfollows. The test time impact of settling times via start/stop motionprofiles is removed. Deterministic, repeatable and quantifiable delaysare introduced between the motion and the measurement of the beam power.Repeatability of measurements across samples sets of AUTs is improveddue to the deterministic relationship between AUT position andmeasurement. The variance of the distribution of results is reduced dueto a reduction in uncertainty of the position/measurement relationship.Additionally, measurement uncertainty of the beam power measurement isremoved due to the adjustable deterministic delay between movementthrough a set spatial location and the measurement of the beam power atthat location.

Calibration with Motion/Data Time Alignment Servomechanism

When adding motion to the measurement set of an AUT/DUT, a potential newsource of measurement uncertainty may be introduced relating to theposition and motion of the AUT that did not previously exist innon-motive test scenarios. This measurement uncertainty contribution tothe overall uncertainty of the reported result may be characterized inisolation by testing the sensitivity of the measurement result (e.g., RFpower) to the absolute location of the RF beam center relative to thecenter of the measurement antenna. Methods in the art for characterizingthis contribution are known in measurement uncertainty models for OTAtesting. However, identifying these sources of error, may not bevaluable when the measurement at a given position is not repeatable overtime or over a single motion profile because the timing alignmentbetween the acquisition of the RF data and the position of AUT arenon-deterministic.

When utilizing the deterministic pulse triggered measurement methoddescribed above, the measured data may be reliably repeated overmultiple AUTs and over different positions along a single AUT profile,as long as no changes are made to the test setup that would affecttiming delays between the motion and measurement components of thesystem.

Some embodiments may implement closed-loop processes on sampled dataflowing through embedded RT processing nodes (e.g., field programmablegate arrays (FPGAs), or other types of processing nodes), that allowin-the-loop adjustment on the data. After setting up themotion/measurement system that relies on triggered pulse trains, thereare timing delays in the system that may have unknown impacts on themeasurement result and the resulting uncertainty computed. To avoidthis, a servomechanism may be implemented as part of a “fast calibrationroutine” that may operate according to the following method steps:

1. Set a fixed beam state/location.

2. Move the positioner back and forth in azimuth and elevation throughthe position that is expected to be delivering the beam center to thetest antenna center.

3. Each time the positioner passes through the set location, it mayproduce a pulse sent to the measurement system to trigger acquisition.

4. An FPGA implemented computation loop may actively find the idealalignment between the trigger position and the computed maximum measuredpower level after that trigger. This alignment time may be used todetermine how many pre-trigger samples should be used for the triggeredacquisition, and how many total samples may be used to compute themeasurement for each AUT location.

The following numbered paragraphs describe additional embodiments:

In some embodiments, an antenna characterization system (ACS) comprisesa chamber, which may be an anechoic chamber; a counter apparatus; aradio frequency (RF) signal analyzer coupled to one or more receiveantennas and the counter apparatus, wherein the one or more receiveantennas are positioned inside the chamber, wherein the RF signalanalyzer is configured to acquire RF measurements made by the one ormore receive antennas of transmissions of an antenna under test (AUT);an adjustable positioner coupled to the counter apparatus; and acomputer comprising a processor and coupled to each of the adjustablepositioner, the counter apparatus, and the RF signal analyzer.

The computer may be configured to initialize a measurement process onthe AUT by causing the adjustable positioner to continually transitionthe AUT inside the chamber through a plurality of orientations withouthalting the motion of the adjustable positioner between orientations,wherein the adjustable positioner is configured to automaticallytransmit a signal through one or more channels to the counter apparatusin response to the adjustable positioner positioning the AUT accordingto each of the plurality of orientations.

In response to receiving the signals from the adjustable positionerthrough the one or more channels, the counter apparatus may beconfigured to modify a first counter value, transmit the modified firstcounter value to the computer, and transmit a first acquisition triggerto the RF signal analyzer, wherein said modifying the first countervalue, transmitting the modified first counter value, and transmittingthe first acquisition trigger occur a plurality of times at differentrespective orientations of the AUT.

The RF signal analyzer may be configured to acquire an RF measurement oftransmissions of the AUT and relay the result of the RF measurement tothe computer in response to receiving each of the plurality of firstacquisition triggers.

The computer may be further configured to correlate the modified firstcounter values received from the counter apparatus with the results ofthe RF measurements to determine an orientation of the plurality oforientations of the AUT corresponding to each of the results of the RFmeasurements, output a correlated list of results of the RF measurementsand their respective orientations of the AUT.

The adjustable positioner may provide direct hardware signaling to thecounter apparatus, and wherein the counter apparatus provides the firstacquisition triggers to the RF signal analyzer through direct hardwaresignaling.

Said continually transitioning the AUT through the plurality oforientations may be performed at a speed such that the time betweensuccessive signal transmissions through each of the one or more channelsis greater than an acquisition time of each of the RF measurements.

Said modifying the first counter value may comprise incrementing ordecrementing the first counter value, and the counter apparatus maycomprise an edge detector configured to detect the front edge in time ofan incremented first counter value and the back edge in time of adecremented first counter value. In these embodiments, said transmittingthe modified first counter value to the computer and said transmittingthe first acquisition trigger to the RF signal analyzer may be performedby the edge detector in response to detecting the front edge of theincremented first counter value or the back edge of the decrementedfirst counter value.

In some embodiments, the counter apparatus comprises a frequencydivisor, and said transmitting the modified first counter value to thecomputer and said transmitting the first acquisition trigger to the RFsignal analyzer is performed by the frequency divisor for every Nthmodified first counter value and every Nth first acquisition trigger,where N is a positive integer.

in response to receiving the signals from the adjustable positionerthrough the one or more channels, the counter apparatus may be furtherconfigured to modify a second counter value, transmit the modifiedsecond counter value to the computer, and transmit a second acquisitiontrigger to the RF signal analyzer, wherein said modifying the secondcounter value, transmitting the modified second counter value, andtransmitting the second acquisition trigger occur a plurality of timesat different respective orientations of the AUT, and wherein the secondcounter value is associated with a different axis of rotation of theadjustable positioner than the first counter value. In theseembodiments, the counter apparatus may comprise a frequency divisor,wherein said transmitting the modified first and second counter valuesto the computer and said transmitting the first and second acquisitiontriggers to the RF signal analyzer is performed by the frequency divisorfor every Nth modified first or second counter value and every Nth firstor second acquisition trigger, where N is a positive integer.

In some embodiments, said acquiring an RF measurement by the RF signalanalyzer is not initiated when one of the plurality of first acquisitiontriggers is received during a previously initiated and ongoing RFmeasurement acquisition. The RF signal analyzer may be furtherconfigured to transmit a reference trigger to the counter apparatus inresponse to initiating each RF measurement acquisition, and saidtransmitting the modified first counter value to the computer by thecounter apparatus may be performed further in response to the counterapparatus receiving the reference trigger from the RF signal analyzer.The RF signal analyzer may be configured to refrain from transmittingthe reference trigger to the counter apparatus when reception of arespective first acquisition triggers does not result in initiation ofacquisition of the RF measurement.

Some embodiments describe a method for measuring transmissions of adevice under test (DUT), the method comprising: by a computer,initializing a measurement process on the DUT by causing an adjustablepositioner to continually transition the DUT inside a chamber through aplurality of orientations without halting the motion of the adjustablepositioner between orientations; automatically transmitting, by theadjustable positioner, a signal through one or more channels to thecomputer in response to the adjustable positioner positioning the DUTaccording to each of the plurality of orientations; in response toreceiving the signals from the adjustable positioner through the one ormore channels, automatically transmitting, by the computer, a sequenceof acquisition triggers to a radio frequency (RF) signal analyzer.

The method may further comprise, by the RF signal analyzer:automatically acquiring an RF measurement of transmissions of the DUTfrom one or more receive antennas positioned inside the chamber inresponse to receiving each of the acquisition triggers in the sequenceof acquisition triggers; and transmitting the results of the RFmeasurements to the computer.

The method may further comprise, by the computer: correlating thesignals received from the adjustable positioner with the results of theRF measurements received from the RF signal analyzer to determine anorientation of the plurality of orientations of the DUT corresponding toeach of the results of the RF measurements; and outputting a correlatedlist of results of the RF measurements and their respective orientationsof the DUT.

In some embodiments, the one or more channels comprise a first channeland a second channel of a quadrature encoder scheme, and the methodfurther comprises: by the computer, determining a direction of motion ofthe DUT based on a relative phase between respective signals of thefirst channel and the second channel, wherein said correlating thesignals received from the adjustable positioner with the results of theRF measurements received from the RF signal analyzer is performed basedon the determined direction of motion.

In some embodiments, said continually transitioning the DUT through theplurality of orientations is performed at a speed such that the timebetween successive signal transmissions through each of the one or morechannels is greater than an acquisition time of each of the RFmeasurements.

In some embodiments, the signals received from the adjustable positionercomprise a first set of signals corresponding to motion of theadjustable positioner around a first axis of rotation, and a second setof signals corresponding to motion of the adjustable positioner around asecond axis of rotation orthogonal to the first axis of rotation.

In some embodiments, said automatically acquiring the RF measurement bythe RF signal analyzer is not performed when an acquisition trigger ofthe sequence of acquisition triggers is received during a previouslyinitiated and ongoing RF measurement acquisition, and the RF signalanalyzer is further configured to transmit a reference trigger to thecomputer in response to performing each RF measurement acquisition. TheRF signal analyzer may be configured to refrain from transmitting thereference trigger to the computer when reception of the respective firstacquisition trigger does not result in the RF measurement acquisition.

Said correlating the signals received from the adjustable positionerwith the results of the RF measurements received from the RF signalanalyzer to determine an orientation of the plurality of orientations ofthe DUT corresponding to each of the results of the RF measurements maybe performed based at least in part on the reference triggers receivedfrom the RF signal analyzer.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

We claim:
 1. An antenna characterization system (ACS), comprising: acomputer comprising a processor coupled to a non-transitory memorymedium; a chamber; a radio frequency (RF) measurement system coupled tothe computer, wherein the RF measurement system is configured to performRF measurements of a device under test (DUT); and an adjustablepositioner positioned within the chamber and coupled to the computer,wherein the adjustable positioner is configured to: position the DUTwithin the chamber according to a plurality of orientations;automatically transmit one or more signals to the computer in responseto the adjustable positioner positioning the DUT according to each ofthe plurality of orientations, wherein the computer is configured to: inresponse to receiving the signals from the adjustable positioner,transmit a plurality of acquisition triggers to the RF measurementsystem to acquire a plurality of RF measurements of the DUT; receiveresults of the plurality of RF measurements from the RF measurementsystem; generate antenna characterization information based at least inpart on the signals received from the adjustable positioner and theresults of the plurality of RF measurements.
 2. The ACS of claim 1,wherein the adjustable positioner comprises hardware sensors configuredto detect the orientation of the adjustable positioner, wherein the oneor more signals are transmitted in response to detection by the hardwaresensors of the adjustable positioner being oriented according to each ofthe plurality of orientations.
 3. The ACS of claim 1, wherein theantenna characterization information is usable to design antennacharacteristics of the DUT.
 4. The ACS of claim 1, wherein in generatingthe antenna characterization information, the computer is configured to:correlate the results of the plurality of RF measurements with thesignals received from the adjustable positioner to determine arespective orientation of the plurality of orientations of the DUTcorresponding to each of the results of the RF measurements; and store acorrelated list of results of the plurality of RF measurements and theirrespective orientations of the DUT in the memory medium.
 5. The ACS ofclaim 1, wherein the computer is further configured to: adjust one ormore counter values based on the signals received from the adjustablepositioner, wherein said correlating the results of the plurality of RFmeasurements with the signals received from the adjustable positionercomprises determining an orientation of the DUT based on the adjustedone or more counter values.
 6. The ACS of claim 1, wherein saidpositioning the DUT within the chamber according to the plurality oforientations comprises continually transitioning the DUT through theplurality of orientations without halting the motion of the adjustablepositioner between orientations.
 7. The ACS of claim 6, wherein saidcontinually transitioning the AUT through the plurality of orientationsis performed at a speed such that the time between successivetransmissions of the one or more signals is greater than an acquisitiontime of each of the RF measurements.
 8. The ACS of claim 1, wherein thecomputer is further configured to: transmit a stop trigger to theadjustable positioner to halt the motion of the adjustable positionerconcurrently with said transmission of each of the acquisition triggersto the RF measurement system, and wherein the RF measurement system isconfigured to: transmit a start trigger to the adjustable positioner toresume the motion of the adjustable positioner upon completion of eachof the RF measurement acquisitions.
 9. The ACS of claim 1, wherein saidtransmission by the adjustable positioner of the one or more signals tothe computer and said transmission by the computer of the plurality ofacquisition triggers to the RF measurement system is performed viadirect hardware signaling.
 10. The ACS of claim 1, wherein the chamberis an anechoic chamber.
 11. A method for performing an antennacharacterization process, the method comprising: by an adjustablepositioner positioned within a chamber and coupled to a computer:positioning a device-under-test (DUT) within the chamber according to aplurality of orientations; and automatically transmitting one or moresignals to the computer in response to the adjustable positionerpositioning the DUT according to each of the plurality of orientations;and by the computer: in response to receiving the signals from theadjustable positioner, transmitting a plurality of acquisition triggersto an RF measurement system to acquire a plurality of RF measurements ofthe DUT; receiving results of the plurality of RF measurements from theRF measurement system; generating antenna characterization informationbased at least in part on the signals received from the adjustablepositioner and the results of the plurality of RF measurements; andstoring the antenna characterization information in a memory.
 12. Themethod of claim 11, wherein the adjustable positioner comprises hardwaresensors configured to detect the orientation of the adjustablepositioner, wherein the one or more signals are transmitted in responseto detection by the hardware sensors of the adjustable positioner beingoriented according to each of the plurality of orientations.
 13. Themethod of claim 11, wherein the antenna characterization information isusable to design antenna characteristics of the DUT.
 14. The method ofclaim 11, wherein in generating the antenna characterization informationcomprises: correlating the results of the plurality of RF measurementswith the signals received from the adjustable positioner to determine arespective orientation of the plurality of orientations of the DUTcorresponding to each of the results of the RF measurements; and storinga correlated list of results of the plurality of RF measurements andtheir respective orientations of the DUT in the memory medium.
 15. Themethod of claim 11, the method further comprising: by the computer:adjusting one or more counter values based on the signals received fromthe adjustable positioner, wherein said correlating the results of theplurality of RF measurements with the signals received from theadjustable positioner comprises determining an orientation of the DUTbased on the adjusted one or more counter values.
 16. The method ofclaim 11, wherein said positioning the DUT within the chamber accordingto the plurality of orientations comprises continually transitioning theDUT through the plurality of orientations without halting the motion ofthe adjustable positioner between orientations.
 17. The method of claim16, wherein said continually transitioning the AUT through the pluralityof orientations is performed at a speed such that the time betweensuccessive transmissions of the one or more signals is greater than anacquisition time of each of the RF measurements.
 18. The method of claim11, the method further comprising: by the computer: transmitting a stoptrigger to the adjustable positioner to halt the motion of theadjustable positioner concurrently with said transmission of each of theacquisition triggers to the RF measurement system, and by the RFmeasurement system: transmitting a start trigger to the adjustablepositioner to resume the motion of the adjustable positioner uponcompletion of each of the RF measurement acquisitions.
 19. The method ofclaim 11, wherein said transmission by the adjustable positioner of theone or more signals to the computer and said transmission by thecomputer of the plurality of acquisition triggers to the RF measurementsystem is performed via direct hardware signaling.
 20. The method ofclaim 11, wherein the chamber is an anechoic chamber.